Minimally Invasive Spinal Stabilization Using Fluoroscopic-Guided Percutaneous Screws as a Form of Palliative Surgery in Patients with Spinal Metastasis

Mun Keong Kwan,Chee Kean Lee,Chris Yin Wei Chan 대한척추외과학회 2016 Asian Spine Journal Vol.10 No.1

Study Design: Prospective cohort study. Purpose: To report the outcome of 50 patients with spinal metastases treated with minimally invasive stabilization (MISt) using fluoroscopic guided percutaneous pedicle screws with/without minimally invasive decompression. Overview of Literature: The advent of minimally invasive percutaneous pedicle screw stabilization system has revolutionized the treatment of spinal metastasis. Methods: Between 2008 and 2013, 50 cases of spinal metastasis with pathological fracture(s) with/without neurology deficit were treated by MISt at our institution. The patients were assessed by Tomita score, pain score, operation time, blood loss, neurological recovery, time to ambulation and survival. Results: The mean Tomita score was 6.3±2.4. Thirty seven patients (74.0%) required minimally invasive decompression in addition to MISt. The mean operating time was 2.3±0.5 hours for MISt alone and 3.4±1.2 hours for MISt with decompression. Mean blood loss for MISt alone and MISt with decompression was 0.4±0.2 L and 1.7±0.9 L, respectively. MISt provided a statistically significant reduction in visual analog scale pain score with mean preoperative score of 7.9±1.4 that was significantly decreased to 2.5±1.2 postoperatively (p =0.000). For patients with neurological deficit, 70% displayed improvement of one Frankel grade and 5% had an improvement of 2 Frankel grades. No patient was bed-ridden postoperatively, with the average time to ambulation of 3.4±1.8 days. The mean overall survival time was 11.3 months (range, 2–51 months). Those with a Tomita score <8 survived significantly longer than those a Tomita score ≥8 with a mean survival of 14.1±12.5 months and 6.8±4.9 months, respectively (p =0.019). There were no surgical complications, except one case of implant failure. Conclusions: MISt is an acceptable treatment option for spinal metastatic patients, providing good relief of instability back pain with no major complications.

Safety of Pedicle Screws in Adolescent Idiopathic Scoliosis Surgery

Chris Yin Wei Chan,Mun Keong Kwan 대한척추외과학회 2017 Asian Spine Journal Vol.11 No.6

To review existing publications on the safety of pedicle screw insertions in adolescent idiopathic scoliosis (AIS). Despite having increased risk for neurological and visceral injuries, the use of pedicle screws have led to increased correction rates in scoliosis surgery. A review was performed on topics pertinent to pedicle screw insertion in AIS, which included pedicle morphometry in AIS, structures at risk during pedicle screw insertion, and accuracy and safety of various pedicle screw insertion techniques. The importance of computer navigation and future research regarding pedicle screw placement in AIS were also briefly reviewed. Many authors have reported abnormal pedicle anatomy in AIS. Injury to the neural structures was highest over the apical region, whereas aortic injury was the highest at T5 and T10. In the proximal thoracic spine, the esophagus could be injured even with screws as short as 25 mm. Overall pedicle perforation rates for perforations >0 and >2 mm (assessed by computed tomography) ranged from 6.4% to 65.0% and 3.7% to 29.9%, respectively. The critical pedicle perforation (>2 mm excluding lateral thoracic) and anterior perforation (>0 mm) rates was reported to range from 1.5% to 14.5% and 0.0% to 16.1%, respectively. Pedicle perforation rates were lower with the use of computer navigation. The incidence of neurological adverse events after scoliosis surgery was 0.06%–1.9%. Aortic injury has only been observed in case reports. According to the available literature, pedicle screw insertion in AIS is considered safe with low rates of clinical adverse events. Moreover, the use of navigation technology has been shown to reduce pedicle perforation rates.

Neurological Recovery in Two Patients with Cauda Equina Syndrome Secondary to L5 Lumbar Spine Giant Cell Tumour after Treatment with Denosumab without Surgery

Simret Singh Randhawa,Angel Khor Nee Kwan,Chee Kidd Chiu,Chris Yin Wei Chan,Mun Keong Kwan 대한척추외과학회 2016 Asian Spine Journal Vol.10 No.5

We report two patients with cauda equina syndrome (CES) secondary to L5 giant cell tumour (GCT) who achieved good neurological recovery after treatment with denosumab without surgery. The first patient was a 26-year-old man with L5 GCT causing CES who regained bowel and urinary control, muscle power improvement from grade 2 to grade 4 and Oswestry disability index (ODI) improvement from 48 to 23 after denosumab treatment. The second patient was a 25-year-old woman with L5 GCT causing CES who regained bowel and urinary control, muscle power improvement from grade 0 to grade 4 and ODI improvement from 42 to 20 after denosumab treatment. The usage of denosumab in the treatment of patients with CES due to GCT allows potential neurological recovery without any surgical intervention. If surgery is not contraindicated, more time is obtained to prepare the patient preoperatively to attain safer surgery and to achieve complete tumour clearance.

Ultra Long Construct Minimally Invasive Spinal Stabilization Using Percutaneous Pedicle Screws in the Treatment of Symptomatic Multicentric Spinal Metastasis

Chee Kean Lee,Chris Yin Wei Chan,Mun Keong Kwan 대한척추외과학회 2015 Asian Spine Journal Vol.9 No.6

Managing multiple level spinal metastases is challenging. We report the case of a 58-year-old female with advanced lung cancer who presented with multiple pathological fractures of the thoracic spine (T5, T6, T7, and T8 vertebrae). She was treated with palliative radiotherapy. Her resting pain improved, but the instability pain persisted. One month later, she had a trivial fall leading to a pathological fracture of the L2 vertebra with cauda equine syndrome. The patient was treated surgically with minimally invasive decompression of the L2 and with percutaneous instrumented stabilization using an ultra-long construct from T3 to L5 (15 spinal levels), spanning the previously radiated zone and the decompression site. Postoperatively, she had significant improvements in pain and neurology. There were no surgical complications. Ultra long construct minimally invasive spinal stabilization is the ideal approach for symptomatic multicentric spinal metastasis with poor prognostic scores. Using this technique, the goals of spinal stabilization and direct neural decompression can be achieved with minimal morbidity.

Surgical Morphometry of C1 and C2 Vertebrae: A Three-Dimensional Computed Tomography Analysis of 180 Chinese, Indian, and Malay Patients

Chee Kean Lee,Tiam Siong Tan,Chris Yin Wei Chan,Mun Keong Kwan 대한척추외과학회 2017 Asian Spine Journal Vol.11 No.2

Study Design: Clinical imaging study. Purpose: To study the surgical morphometry of C1 and C2 vertebrae in Chinese, Indian, and Malay patients. Overview of Literature: C1 lateral mass and C2 pedicle screw fixation is gaining popularity. However, there is a lack of C1–C2 morphometric data for the Asian population. Methods: Computed tomography analysis of 180 subjects (60 subjects each belonging to Chinese, Indian, and Malay populations) using simulation software was performed. Length and angulations of C1 lateral mass (C1LM) and C2 pedicle (C2P) screws were assessed. Results: The predicted C1LM screw length was between 23.2 and 30.2 mm. The safe zone of trajectories was within 11.0°±7.7° laterally to 29.1°±6.2° medially in the axial plane and 37.0°±10.2° caudally to 20.9°±7.8° cephalically in the sagittal plane. The shortest and longest predicted C2P screw lengths were 22.1±2.8 mm and 28.5±3.2 mm, respectively. The safe trajectories were from 25.1° to 39.3° medially in the axial plane and 32.3° to 45.9° cephalically in the sagittal plane. Conclusions: C1LM screw length was 23–30 mm with the axial safe zone from 11° laterally to 29° medially and sagittal safe zone at 21° cephalically. C2P screw length was 22–28 mm with axial safe zone from 26° to 40° medially and sagittal safe zone from 32° to 46° cephalically. These data serve as an important reference for Chinese, Indian, and Malay populations during C1–C2 instrumentation.

Cervical Supine Side-Bending versus Cervical Supine Traction Radiographs: Which Is Better in Predicting Proximal Thoracic Flexibility for Lenke 1 and 2 Adolescent Idiopathic Scoliosis?

Chee Kidd Chiu,Elrofai Suliman Bashir,Chris Yin Wei Chan,Mun Keong Kwan 대한척추외과학회 2018 Asian Spine Journal Vol.12 No.4

Study Design: Prospective cohort study. Purpose: This study compared cervical supine side-bending (CSSB) and cervical supine traction (CST) radiographs to assess the flexibility and predict the correctability of the proximal thoracic (PT) curve for patients with adolescent idiopathic scoliosis (AIS) classified as Lenke 1 and 2. Overview of Literature: Knowledge of the flexibility of the PT curve is crucial in the management of patients with AIS. There are no reports comparing CSSB and CST radiographs to assess this parameter. Methods: Thirty patients with Lenke 1 and 2 AIS scheduled for posterior spinal fusion surgery were recruited. A standing whole spine radiography and physician-supervised CSSB and CST radiographies were performed. Patient demographic and radiological parameters were recorded, including age, gender, weight, height, body mass index, PT angle, main thoracic angle, CSSB PT angle, CST PT angle, and postoperative PT angle. From the data collected, the curve flexibility and curve correction index were calculated and compared. Results: CSSB had a significantly (p<0.05) smaller PT angle (16.6°±10.4°) in comparison to CST (23.7°±10.7°). CSSB had significantly (p<0.05) greater flexibility (44.2%±19.7%) in comparison to CST (19.5%±18.1%). The CSSB correction index (1.2±0.9) was significantly closer to 1 in comparison to the CST correction index (4.4±5.3). There was no difference (p=0.72) between the CSSB PT angle (16.6°±10.4°) and the postoperative PT angle (16.1°±7.5°). However, the CST PT angle (23.7°±10.7°) was significantly (p<0.05) larger than the postoperative PT angle (16.1°±7.5°). Conclusions: CSSB radiographs were better for demonstrating PT flexibility and more accurately predicted correctability in comparison to the CST radiographs.

APSS-ASJ Best Clinical Research Award: Is There a Difference between Patients’ and Parents’ Perception of Physical Appearance in Adolescent Idiopathic Scoliosis?

Chris Yin Wei Chan,Siti Mariam Abd Gani,Min Yuen Lim,Chee Kidd Chiu,Mun Keong Kwan 대한척추외과학회 2019 Asian Spine Journal Vol.13 No.2

Study Design: Prospective study. Purpose: To compare patients’ and parents’ perceptions of physical attributes (PAs) of adolescent idiopathic scoliosis (AIS) patients and to report any correlations between their perceptions and Scoliosis Research Society-22r (SRS-22r) scores. Overview of Literature: Few studies have looked into the differences between patients’ and parents’ perceptions of their appearance. Methods: AIS patient–parent pairs (n=170) were recruited. The patients’ and parents’ perceptions of six PAs were evaluated: waist asymmetry (WA), rib hump (RH), shoulder asymmetry (SA), neck tilt, breast asymmetry (BrA), and chest prominence. These PAs were ranked, and an aggregate PA (Agg-PA) score was derived from a score assigned to the attribute (6 for the most important PA and 1 for the least important). The patients also completed the SRS-22r questionnaire. Results: Ninety-nine patients (58.2%) and 71 patients (41.8%) had thoracic and lumbar major curves, respectively. WA was ranked first by 54 patients (31.8%) and 50 parents (29.4%), whereas RH was ranked first by 50 patients (29.4%) and 38 parents (22.4%). The overall Agg-PA scores were similar for patients and parents (p>0.05). However, for thoracic major curves (TMCs) >40°, a significant difference was noted between the Agg-PA scores of patients and parents for SA (3.5±1.6 vs. 4.2±1.6, p=0.041) and BrA (3.0±1.6 vs. 2.2±1.3, p=0.006). For TMCs <40°, a significant difference was found between the Agg-PA scores of patients and parents for WA (3.7±1.6 vs. 4.4±1.5, p=0.050). BrA was negatively correlated with total SRS-22r score. Conclusions: There were no significant differences between patients and parents in their ranking of the most important PAs. For TMCs >40°, there were significant differences in the Agg-PA for SA and BrA. Pa¬tients were more concerned about BrA and parents were more concerned about SA. Patients’ perception of the six PAs had weak correlation with SRS-22r scores.

Variations in Practice among Asia–Pacific Surgeons and Recommendations for Managing Cervical Myelopathy: The First Asia–Pacific Spine Society Collaborative Study

Jason Pui Yin Cheung,Prudence Wing Hang Cheung,Chee Kidd Chiu,Chris Yin Wei Chan,Mun Keong Kwan 대한척추외과학회 2019 Asian Spine Journal Vol.13 No.1

Study Design: Surgeon survey. Purpose: To study the various surgical practices of different surgeons in the Asia–Pacific region. Overview of Literature: Given the diversity among Asia–Pacific surgeons, there is no clear consensus on the preferred management strategies for cervical myelopathy. In particular, the role of prophylactic decompression for silent cervical spinal stenosis is under constant debate and should be addressed. Methods: Surgeons from the Asia–Pacific Spine Society participated in an online questionnaire comprising 50 questions. Data on clinical diagnosis, investigations and outcome measures, approach to asymptomatic and silent cervical spinal stenosis, guidelines for surgical approach, and postoperative immobilization were recorded. All parameters were analyzed by the Mantel–Haenszel test. Results: A total of 79 surgeons from 16 countries participated. Most surgeons used gait disturbance (60.5%) and dyskinetic hand movement (46.1%) for diagnosis. Up to 5.2% of surgeons would operate on asymptomatic spinal stenosis, and 18.2% would operate on silent spinal stenosis. Among those who would not operate, most (57.1%) advised patients on avoidance behavior and up to 9.5% prescribed neck collars. For ossification of the posterior longitudinal ligament (OPLL), anterior removal was most commonly performed for one-level disease (p <0.001), whereas laminoplasty was most commonly performed for two- to four-level disease (p =0.036). More surgeons considered laminectomy and fusion for multilevel OPLL. Most surgeons generally preferred to use a rigid neck collar for 6 weeks postoperatively (p <0.001). Conclusions: The pooled recommendations include prophylactic or early decompression surgery for patients with silent cervical spinal stenosis, particularly OPLL. Anterior decompression is primarily suggested for one- or two-level disease, whereas laminoplasty is preferred for multilevel disease.

Feasibility of Single-Stage Posterior Passive Correction and Fusion Surgery for Congenital Scoliosis in Adolescent Patients Who Have Attained Skeletal Maturity

Chiu Chee Kidd,Tan Rommel Lim,Gani Siti Mariam Abd,Chong Jessamine Sze Lynn,Chung Weng Hong,Chan Chris Yin Wei,Kwan Mun Keong 대한척추외과학회 2022 Asian Spine Journal Vol.16 No.3

Study Design: Retrospective study.Purpose: To report the perioperative and radiological outcomes of single-stage posterior passive correction and fusion (SSPPCF) in adolescent patients who present with congenital scoliosis.Overview of Literature: The surgical treatment for congenital scoliosis is complex. There is no definitive guide on surgical options for skeletally matured adolescent patients who have congenital scoliosis.Methods: Patients with congenital scoliosis who underwent SSPPCF using a pedicle screw system were reviewed. We identified the following three surgical indications: (1) hemivertebra or wedge vertebra over the thoracic or thoracolumbar region with structural lumbar curves, (2) hemivertebra or wedge vertebra at the lumbar region with significant pelvic obliquity or sacral slanting, and (3) mixed or complex congenital scoliosis. The demographic, perioperative, and radiographic data of these patients were collected.Results: Thirty-four patients were reviewed. The mean patient age was 14.6±3.4 years. There were 13 hemivertebrae, three wedged vertebrae, two butterfly vertebrae, three hemivertebrae with butterfly vertebra, eight unsegmented bars, and five multiple complex lesions. The average surgical duration was 219.4±68.8 minutes. The average blood loss was 1,208.4±763.5 mL. Seven patients required allogeneic blood transfusion. The mean hospital stay duration was 6.1±2.5 days. The complication rate was 11.8% (4/34): one patient had severe blood loss, one had rod breakage, and two had distal adding-on. The Cobb angle reduced from 65.9°±17.4° to 36.3°±15.3° (p<0.001) with a correction rate (CR) of 44.8%±17.4%. The regional kyphotic angle decreased from 39.9°±20.5° to 27.5°±13.9° (p=0.001) with a CR of 19.3%±49.6%. Radiographic parameters (radiographic shoulder height, clavicle angle, T1 tilt, cervical axis, pelvic obliquity, coronal balance, and apical vertebral translation) showed significant improvement postoperatively.Conclusions: SSPPCF was a feasible option for adolescent patients with congenital scoliosis who were skeletally matured.

Validation Study of Rajasekaran’s Kyphosis Classification System: Do We Clearly Understand Single- and Two-Column Deficiencies?

Ajoy Prasad Shetty,Rajesh Rajavelu,Vibhu Krishnan Viswanathan,Kota Watanabe,Harvinder Singh Chhabra,Rishi Mukesh Kanna,Jason Pui Yin Cheung,Yong Hai,Mun Keong Kwan,Gabriel Liu,Gabriel Liu,Saumajit Bas 대한척추외과학회 2020 Asian Spine Journal Vol.14 No.4

Study Design: Multicenter validation study.Purpose: To evaluate the inter-rater reliability of Rajasekaran’s kyphosis classification through a multicenter validation study.Overview of Literature: The classification of kyphosis, developed by Rajasekaran, incorporates factors related to curve characteristics, including column deficiency, disc mobility, curve magnitude, and osteotomy requirements. Although the classification offers significant benefits in determining prognosis and management decisions, it has not been subjected to multicenter validation.Methods: A total of 30 sets of images, including plain radiographs, computed tomography scans, and magnetic resonance imaging scans, were randomly selected from our hospital patient database. All patients had undergone deformity correction surgery for kyphosis. Twelve spine surgeons from the Asia-Pacific region (six different countries) independently evaluated and classified the deformity types and proposed their surgical recommendations. This information was then compared with standard deformity classification and surgical recommendations.Results: The kappa coefficients for the classification were as follows: 0.88 for type 1A, 0.78 for type 1B, 0.50 for type 2B, 0.40 for type 3A, 0.63 for type 3B, and 0.86 for type 3C deformities. The overall kappa coefficient for the classification was 0.68. Regarding the repeatability of osteotomy recommendations, kappa values were the highest for Ponte’s (Schwab type 2) osteotomy (kappa 0.8). Kappa values for other osteotomy recommendations were 0.52 for pedicle subtraction/disc-bone osteotomy (Schwab type 3/4), 0.42 for vertebral column resection (VCR, type 5), and 0.30 for multilevel VCRs (type 6).Conclusions: Excellent accuracy was found for types 1A, 1B, and 3C deformities (ends of spectrum). There was more variation among surgeons in differentiating between one-column (types 2A and 2B) and two-column (types 3A and 3B) deficiencies, as surgeons often failed to recognize the radiological signs of posterior column failure. This failure to identify column deficiencies can potentially alter kyphosis management. There was excellent consensus among surgeons in the recommendation of type 2 osteotomy; however, some variation was observed in their choice for other osteotomies.